FW: <E36> Water Pump Failures

["Sanders, Ron" <rls5@xxxxxxx>]

>     Reading Jason Euculano's water pump failure in V09, #514 I suspect the
> root cause of the water pump failures is the seal leaking between the
> impeller and bearings.  Once the seal starts to leak coolant mixes with
> the
> bearing lubricant and the bearings start to fail.  As this occurs the
> pulley
> belt load causes the right side fan to move forward and contact the
> radiator.    Unfortunately, there isn't any warning of the incipit
> failure,
> that is any type of squeal or grinding noise due to the fact that the
> water
> pump is in the block.  (As compared to the water pump mounted on a Chevy
> 350
> or 427).  Also, there is no vent hole in the housing, if there was a vent
> hole as there are on many cars, coolant leaking out of the vent would be a
> clear warning that the seal had started to leak.  Actually this would
> prevent the bearings from failing as the coolant would not get into the
> lubricant.
> 
>     Thinking this through here are a couple of things that may give you a
> warning that the bearings are starting to fail.  The first is a small, no
> more than a cup, but sudden drop in the radiator coolant level and it only
> happens once.  The seal has start to leak and has filled the water pump
> body.  Another way is to look at the fan, if the right side is sticking
> farther in the radiator shroud than the left side the bearings have
> clearly
> failed and are loose.  The belt load on the water pump is pulling the pump
> shaft to the left and that's why the fan is not square in relation to the
> radiator shroud.  The most positive way to check the water pump is to
> loosen
> the serpentine belt tensioning pulley and see if you can wobble the fan,
> if
> so it is a sure sign that the bearings have failed.
> 
>     I decided to replace it while I was doing my Inspection II.  Since I
> was
> going to replace my belts and it is recommended to take the fan clutch off
> to gain access to the tensioning pulley I figured I might as well do it as
> all I remaining is to do is remove the water pump.  My build date was
> 9/93,
> the impeller appears to be more like a urethane like material as it was
> flexible, I'm not sure if it is the same plastic material that was on the
> earlier pumps.  The replace pump had a steel impeller and it only cost
> $71.00 with the BMWCCA discount.  I do a fair amount of long distant
> traveling on the weekends and don't want to break down 100 miles from
> nowhere as Jason almost did.
> 
>     Here are the parts and tools you'll need:
>         - Water pump
>         - Several 6mm water pump shoulder nuts (If you drop one you'll
> never
>             find it,  just like I can't find one of my 10mm sockets.  Also
>             used many other places on the engine.)
>         - Three 6mmx30mm bolts (Cut the head off of one so it can be used
> as
>             a pilot stud.)
>         - One 6mm bolt for the fan clutch (Just spare in case you drop one
>             of them).
>         - Fan clutch wrench - 32mm or 1-5/16 inch (Bought mine at a
> bicycle
>             shop, if I remember correctly it's called a head spacer wrench
> -
>             Parks HCW7 30mm/32mm open end.  I was told Snap On made it for
>             Parks).
>        -  M8 hex socket for relaxing the A/C tension pulley (Actually I
> used
>             a M8 hex wrench and put a box wrench on for additional
> leverage
> as
>             I didn't want to stop and go out and buy the hex socket-
> worked
> OK
>              as the tensioner has a low preload.)
>         - 18inx15in piece of cardboard.
> 
> Now finally to the pump replacement:
>     1.  Raise front end
>     2.  Drain coolant
>     3.  Remove radiator shroud retainers and move shroud back
>     4.  Slide the cardboard down behind the radiator to prevent any
> bending
>         the radiator fins.
>                 (Didn't have a fin comb to straighten the fins)
>     5.  Raise the shroud up enough so it can be brought froward over the
>         radiator and held up by the radiator.
>                 (It will give you the space you need to slide the fan,
>                 clutch and water pump out.)
>     6.  Loosen the fan clutch and fan using the 32mm wrench, don't forget
> it
>         has left hand threads so you loosen in a clockwise direction.
>                 (If the pulley slips either jam a rag between it and the
>                 belt or take one pulley bolts out and thread the stud in
> and
> use a
>                 screwdriver to prevent it from rotating).
>     7.  Remove the covers off the tensioning pulleys using a screwdriver.
>     8.  From underneath mark the belt rotation and loosen the A/C
> tensioning
>                 pulley using the M8 hex socket and remove the  belt.
>     9.  Mark the belt rotation and remove the serpentine belt.
>                 (I had to use a 15mm socket on mine, I think the earlier
>                 ones may need a hex socket)
>     10. Back on top remove the pump pulley bolts and remove the pulley.
>                 (Look at the pulley's bolt pattern you'll see one is
> offset,
>                 just remember this when you put it on.)
>     11. Look at the new pump you'll see the four mounting holes and two
>                 threaded holes.
>     12. Loosen the four pump mounting nuts using a 10mm socket and thread
>                 the two 6mm bolts into the pump body.
>      13. Using a 10mm socket alternate tightening the bolts, as you do
> this
>                 you'll see the pump sliding down the studs and then freely
> coming off.
>                (Oh yeah, don't forget to put something under to catch the
>                 coolant as the pump comes off!)
> 
>        Time for a break and a Corona!!!
> 
>     14.  Put the pilot stud in the water pump pulley hole that is offset.
>     15.  Lubricate the pump 'O' ring with some antifreeze.
>     16.  Slide the pump back on the studs, install the nuts and tighten.
>                 (You may be able to only start one of the nuts; if so,
> push
>                 on the pump so there is sufficient treads to start the
> rest
>                 of the nuts).
>     17. Index and reinstall the pulley, bolts and tighten.
>     18. Reinstall serpentine and A/C belts.
>     19. Reinstall the fan clutch and fan tightening in a counterclockwise
>            direction.
>     20. Remove the cardboard and reposition the fan shroud and install
>             fasteners.
>     21. Fill the radiator and start the engine, refill and install
> radiator
> cap.
>     22. After the engine is warm open the bleeder screw next to the
> radiator
>             cap, when coolant comes out in a steady trickle close the
> bleeder
>             screw.   Stop the engine.
>     23.  Top off the radiator after the engine has cooled down.
> 
>             That's IT!!!
> 
>     I'd like to hear from any of you that have had failures to see if my
> assumptions were correct.  Also, from anyone else that has comments on the
> procedure.
> 
> Dennis Eichstaedt
> Canton, Michigan
> 325iA
> BMWCCA 144816
> 
> 
> 
> 

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